This invention relates to a method and apparatus for determining the length of at least one of two legs of a part, which legs have been bent toward each other by means of a bending tool at a bending angle whose vertex is at the point of intersection of the straight, angle defining projections of the legs of the bent part, with one end of the leg to be measured delimiting the latter on the far side opposite the vertex of the bending angle. The invention further relates to a method and a device for bending workpieces utilizing the aforementioned method and apparatus for determining the length of the leg of a bent part.
Excluding the bending angle, the length of the legs is the most important functional measure of a bent part. The conventional method heretofore used to determine the length of a leg of a part bent in a bending machine has been to take the part out of the bending machine and measure it manually. The accuracy of that measurement of the length is compromised primarily by the fact that, at the apex of the bent part, the legs that are to be measured do not meet in an ideal, straight line but instead converge in an arcuate contour or radiused fashion. Thus, the vertex of the bending angle does not really constitute one of the end points of the leg of a bent part and the point of intersection of the straight projections of both legs. Therefore, it is not possible, for instance, to directly gauge the vertex of the bending angle within the determination of the length of the leg of a bent part. Particular difficulties that can be overcome only by means of complex metrology are encountered in the case of open bending angles, i.e., included angles of more than 90°.
It is an objective of this invention to provide apparatus that permits an automated and highly accurate determination of the length of the legs of bent parts with a particular view to the optimization of the workpiece bending processes.
Another objective is to provide a method which accurately and quickly measures the length of the legs of the bent parts.